Railway-traffic-controlling apparatus



geptq 27, 192?.

. 1,643,331 P. N. BOSSART RAILWAY TRAFFIC CONTROLLING APPARATUS Filed June 30, 1926 INVENTOR Patented Sept. 27, 1927.

UNETED STATES PAUL N. BOSSABT, OF SWISSVALE, PENN$YLVANIA, Ar

8s SIGNAL COMPANY, OF SWISSVALE, PENNSYLVAIILA, If

SYLVANIA.

NT filth-FEE.

BT03 310 THE "UNION SWITCH QRE'SHATION OF PENN- PAT RAILWAY-TRAFFIC-CONTROLLING APPARATUS.

Application filed June 30, 1926.

My invention relates to railway traflic controlling apparatus, and particularly to appa ratus of the type comprising train carried governing means controlled by train controlling current flowing in the trackway.

One object of my present invention is the provision of apparatus of the type described which is immune to the vellects of straycurrents flowing in the trackway or in adjacent conductors such as transmission lines etc.

I will describe one form of railway trafiic controlling a] paratus embodying my inven-' tion, and will then point out the novel teatures thereof in claims.

The accompanying drawing is a diagrammatic view, illustrating one form of railway tratfic controlling apparatus embodying my invention.

Referring to the drawing, the reference characters 1 and 1 designate the track rails of a stretch of railway track. These rails are at times supplied with alternating train controlling current from a suitable source such as an alternator G which is connected across the rails through a circuit controller 21. In actual practice the circuit controller 21 will usually be controlled by traflic conditions. hen this circuit controller is closed alternating train controlling current is supplied to the track rails, and when the circuit controller is open this supply is interrupted.

Carried on the t 'ain are two magnetizable cores 2 and 9f located in inductive relation with the two track rails 1 and l respec tively. Core 2 is provided with a winding 3, and core 2 is provided with a similar winding 3, these two windings being connccted in series in such manner that the voltages induced therein by train controlling currents flowingin the two track rails 1 and 1 at an instant are additive. The windings 3 and 3 control an amplifier A. 1 In the form here shown this amplifier is of the microphone type and comprises a permanent magnet 7 and a vibrating armature 8. The armature 8 carries a winding 6 which is con nccted with windings 3 and 3 through a condenser 4 and a resistance 5; The circuit including the windings 3 and 3, the condenser 41 the resistance 5, andthe operating win-ding 6 of the amplifier A is designated in gen,- eral'by the reference character D, and I shall refer to this circuit hereinatter'as the Serial No. 119,617.

pick-up circuit. The armature 8 of the amplifier A controls a microphone unit B comprising a fixed tube 2? of insulating material containing a conducting plug 9. A mass 10 of carbon granules or grains is interposed between this plug 9 and a movable plunger 11 of conducting material which is operatively connected with armature 8. It will therefore be plain that vibration of the armature 8 will cause movement of the plunger 11 which will in turn vary the pressure on the carbon granules l0 and will therefore vary the resistance of the microphone unit. The primary 12 of a transformer is connected in series with a source or" direct current, such as battery 13, and the microphone unit B, so that operation of the amplifier A. causes pulsations in the current supplied to the primary of the transformer.

The secondary 14- of transformer T supplies energy to a filter circuitdesignated in general. by the reference character J and comprisingan auto transtormer M and a condenser i6. it direct current relay K is connected with windings l8 and 19 0t transformer M through rectifiers 20 and 21 so that alternating current flow. r g in the transformer M due to pulsatii'ins in the current in winding 12 of transformer T energizes relay K.

The parts are so arranged that the reactive impedanceof winding 1? cl transformer M is very high compared with the reactive impedance oi windings 8 and 19, and the circuit is tuned by means of condenser 16 so that the circuit J comprises a band pass filter of the simple resonant circuit type. The parts are further proportioned so that the decrement of the filter circuit is low in order to obtain sharp filtering.

Relay i controls governing means of any suitable form, iere shown as two lamps 24; and When relay energized, current flows from, a sui able source of energy, suchas a battery 1 front contact 23* otrelay When rclay 11: is de-enc is closed and; on thron g'h lamp 25. c

When train controlling current is flowing through the track rails the voltages induced in windings and 5? cause a current in the pick-up circuit D which operates the amplifier A. The resultingpulsations in the priinary 12 of transformer T cause an alternating current in the filter circuit J which energizes relay K and causes lamp 2% to become l htet. When the supply of train controlling current to the traclrway becomes interrupted the operation of the amplifier A is discontinued and relay K becomes de-energized thereby lighting lamp 25.

Under some condi ions of operation it may happen that currents are created in the pick-up circuit D when no train controlling current is being supplied to the track rails. This may result from stray alternating currents in the track rails or it may occur from heavy pulsations of direct or alternating currents either in the track rails or in conductors adjacent the trackway. In the absence of any preventative means these currents cause improper operation of the train carried lamps. I therefore proportion the various parts of the train carried apparatus in such manner that the effect of these stray currents is successively diminished as the currents pass through the apparatus so that their effect upon relay K is negligible. By means of the condenser 4 the pick-up circuit D is tuned to resonance at a frequency slightly below the frequency of the train controlling current. By means of the resistance 5 this pick-up circuitis adjusted to have a high decrement so that the alternating current created in th pick-up circuit by pulse excitation from surges of stray currents will die down rapidly. I also construct the amplifier A so that it. mechanically untuned. The purpose of this construction is to preventmechanical shocks due to heavy pulses of current in the pick-up circuit from setting up in the amplifier vibrations of the frequency of the train controlling current. It follows that the effect of stray currents induced at train control frequency in the pickup circuit by heavy surges of current in the vicinity of the pick-up circuit is greatly reduced, both as to amount and as to the length of time the excitation from any one pulse will be of sutliciently high value to actuate the microphone through its normal amplitude.

It is well known that at a given frequency, the output of a microphone amplifier has a definite saturation point and that increasing the input to winding 6 above this definite saturation point will cause substantially no increase in the output of the amplifier. On the other hand, an increase in the input to the amplifier above this saturation point will react to detune the pick-up circuit, because of the variation in the permeability of the magnetizable cores 2, 2, and the magnet 7 and armature 8 in response to variations in the magnetizing force. The effect of this detuning is to lower the resonant frequency of the circuit and it follows that the effect of surges on the amplifier is to increase the difference between the resonant frequency of the circuit D and the frequency of the train controlling current.

The parts are so proportioned that for normal values of train cont-rolling current the amplifier A operates just below the saturation point. It follows that increased currents in the pick-up circuit due to stray cur rents in this circuit simnltaneous'with the currents induced in this circuit by train controlling current will not cause a substantial increase in the output of the amplifier but may even cause a slight decrease in the output.

Due to the sharp tuning and low decrement of the filter circuit J should any surge pass the amplifier A, a considerable time, that is, a considerable number of cycles, is required before the resulting current will build up in circuit J to the value required to operate relay K.

Furthermore the circuit J is tuned to resonance at a frequency slightly greater than the frequency of the train controlling current so that the difference between the resonant frequencies of circuitsD and J is considerable, though neither is sutliciently mistuned to the traincontrolling current to substantially affect the resonant response to current of train control frequency.

Considering the operation of the apparatus as a whole, it will. be seen that stray currents caused by shock excitation of circuit D will be of the frequency to which this circuit is tuned, and therefore slightly below the frequency of the train controlling current. Due to the high decrement of circuit D this current will die out very rapidly. During thefirst few cycles of this stray cur rent amplifier A may be operated, but the amplifier will be saturated and will not increase its output. The reaction of the pickup circuit to large currents flowing in itself will further Inistune the pickup circuit. The only effect of the free oscillations in circuit D, therefore, is to create stray current of a similar frequency in the transformer T and hence in the filter circuit J. But the stray current will be of considerably lower frequency than the frequency to which the filter circuit is tuned and the filter will therefore substantially block the stray current. Furthermore, due to the sharp tuning and low decrement of circuit J. the stray current in circuit D will have died out before the resulting current in relay K has grown to an amount sufficient to energize the relay. The effect of stray currents upon relay K istherefore negligible.

It will be plain from the foregoing that if no train controlling current is being supplied to the track rails, stray transient cur rents induced in the pick-up circuit D will not operate relay K to give a false indication by lighting lamp 24. Similarly, a continuous alterating current induced in the pick-up circuit D even if sufficient in magnitude to operate amplifier A through its normal or even greater amplitude, can create only a predetermined value of pulsating current in primary 12. But the resulting current in secondary 14, unless very close to the frequency band passed by the filter circuit J, will be so attenuated that it will be insufficient to operaterelay K.

Although I have herein shown and described only one form of railway traffic controlling apparatus embodying my invention. it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Railway traffic controlling apparatus comprising a transformer, means on the train controlled from the trackway for supplying energy to the primary of said transformer, a reactance and a condenser con nected in series with the secondary of the transformer, and governing means controlled by the voltage across a portion of said reactance.

2. Railway trafiic controlling apparatus comprising a transformer, means on the train controlled from the trackway for supplying energy to the primary of said transformer, a tuned filter circuit for the secondary of said transformer including a condenser and an auto-transformer, and governing means controlled by said auto-transformer.

3. Railway traffic controlling apparatus comprising a tuned pick-up circuit on the train receiving energyfrom the rails, governing means on the train, a tuned filter circuit for controlling such governing means, and a mechanically untuned microphone amplifier for transferring energy from said pick-up circuit to said filter circuit.

4. In combination, a stretch of railway track supplied with alternating train controlling current, a tuned pick-up circuit on a train receiving energy from the trackway, an amplifier controlled by said pick-up circuit and substantially saturated by normal values of said train controlling current, governing means on the train controlled by said amplifier, and a band pass filter interposed between said amplifier and said governing means, said pick-up circuit being tuned to resonance at a frequency slightly different from the output frequency of said filter.

5. In combination with a stretch of track supplied with alternating train controlling current, a train carried pick-up circuit inductively related to the trackway, and tuned to resonance at a frequency slightly below the frequency of said train controlling ourrent, a filter circuit tuned to resonance at a frequency slightly above the frequency of said train controlling current, an amplifier for transferring energy from said pick-up circuit to said filter circuit and governing means controlled by said filter circuit;

6. In combination with a stretch of track supplied with alternating train controlling current, a train carried pick-up circuit inductively related to the traclrway and tuned to resonance at a frequency slightly below the frequency of said train controlling current, a filter circuit tuned to resonance at a frequency slightly above the frequency of said train controlling current, a mechanically untuned microphone amplifier for transferring energy from said pick-up circuit to said filter circuit, and governing means controlled by said filter circuit.

7. In combination with a stretch of track supplied with alternating train controlling current, a train carried pick-up circuit inductively related to the trackway, and tuned to resonance at a frequency slightly below the frequency of said train controlling current, a mechanically untuned microphone amplifier controlled by said pick-up circuit and substantially saturated at normal values of the train controlling current, a train carried relay, a band pass filter interposed between said amplifier and said relay, and governing means controlled by said relay.

8. In combination with a stretch of railway track supplied with alternating current, a tuned pick-up circuit receiving energy from the trackway, an untuned amplifier controlled by said pick-up circuit, a tuned filter circuit receiving ener y from said amplifier, and a relay controlled by said filter circuit, said pick-up circuit having a high decrement and said filter circuit hav ing a low decrement so that the currents caused in the picleup circuit by a surge of energy in the trackway will dieout before the resulting currents in the filter circuit grow to a magnitude sufiicient to energize said relay.

9. In combination with a stretch of railway track supplied with alternating current, a magnetizable core located in inductive relation with the track rails, a winding 011 said core, a pick-up circuit including said winding and normally mistuned slightly to the frequency of such current so that the variation in the permeability of said core due to a surge of energy in the trackway will further mistune said pick-up circuit, an amplifier controlled by the pick-up circuit, a relay, and a band pass filter interposed between said relay and said amplifier.

10. In combination with a stretch of rail way track supplied with alternating current, a tuned pick-up circuit receiving energy from the trackway, an untuned amplifier controlled by said pick-up circuit and subeases;

rents caused in the pick-up circuit by a surge of energy in the trackway Will die out before the resulting currents in the filter circuit 10 grow to a, magnitude usufliclent to energize said relay.

In testimony whereof I affix my signature.

PAUL N. BOSSA'RT. 

